A critical zone observatory dedicated to suspended sediment transport: The meso-scale Galabre catchment (southern French Alps)     

Cédric Legout  Guilhem Freche  Romain Biron  Michel Esteves  Oldrich Navratil  Guillaume Nord  Magdalena Uber  Thomas Grangeon  Nico Hachgenei  Brice Boudevillain  Céline Voiron  Lorenzo Spadini 《水文研究》2021,35(3):e14084

The 20 km² Galabre catchment belongs to the French network of critical zone observatories (OZCAR; Gaillardet et al., Vadose Zone Journal, 2018, 17(1), 1–24). It is representative of the sedimentary lithology and meteorological forcing found in Mediterranean and mountainous areas. Due to the presence of highly erodible and sloping badlands on various lithologies, the site was instrumented in 2007 to understand the dynamics of suspended sediments (SS) in such areas. Two meteorological stations including measurements of air temperature, wind speed and direction, air moisture, rainfall intensity, raindrop size and velocity distribution were installed both in the upper and lower part of the catchment. At the catchment outlet, a gauging station records the water level, temperature and turbidity (10 min time-step). Stream water samples are collected automatically to estimate SS concentration-turbidity relationships, allowing quantification of SS fluxes with known uncertainty. The sediment samples are further characterized by measuring their particle size distributions and by applying a low-cost sediment fingerprinting approach using spectrocolorimetric tracers. Thus, the contributions of badlands located on different lithologies to total SS flux are quantified at a high temporal resolution, providing the opportunity to better analyse the links between meteorological forcing variability and watershed hydrosedimentary response. The set of measurements was extended to the dissolved phase in 2017. Both stream water electrical conductivity and major ion concentrations are measured each week and every 3 h during storm events. This extension of measurements to the dissolved phase will allow progress in understanding both the origin of the water during the events and the partitioning between particulate and dissolved fluxes of solutes in the critical zone. All data sets are available at https://doi.osug.fr/public/DRAIXBLEONE_GAL/index.html .  相似文献   

Origin of sulphate in the unsaturated zone and groundwater of a loess aquifer     

Yin Long  Tianming Huang  Fen Zhang  Zhenbin Li  Baoqiang Ma  Yiman Li  Zhonghe Pang 《水文研究》2021,35(4):e14166

The use of the sulphate mass balance (SMB) between precipitation and soil water as a supplementary method to estimate the diffuse recharge rate assumes that the sulphate in soil water originated entirely from atmospheric deposition; however, the origin of sulphate in soil and groundwater is often unclear, especially in loess aquifers. This study analysed the sulphur (δ³⁴S-SO₄) and oxygen (δ¹⁸O-SO₄) isotopes of sulphate in precipitation, water-extractable soil water, and shallow groundwater samples and used these data along with hydrochemical data to determine the sources of sulphate in the thick unsaturated zone and groundwater of a loess aquifer. The results suggest that sulphate in groundwater mainly originated from old precipitation. When precipitation percolates through the unsaturated zone to recharge groundwater, sulphates were rarely dissolved due to the formation of CaCO₃ film on the surface of sulphate minerals. The water-extractable sulphate in the deep unsaturated zone (>10 m) was mainly derived from the dissolution of evaporite minerals and there was no oxidation of sulphide minerals during the extraction of soil water by elutriating soil samples with deionized water. The water-extractable concentration of SO₄ was not representative of the actual SO₄ concentration in mobile soil water. Therefore, the recharge rate cannot be estimated by the SMB method using the water-extractable concentration of SO₄ in the loess areas. This study is important for identifying sulphate sources and clarifying the proper method for estimating the recharge rate in loess aquifers.  相似文献   

Drying increases organic colloidal mobilization in the karst vadose zone: Evidence from a 15-year cave-monitoring study     

Jin Liao  Chaoyong Hu  Xiuli Li  Jiaoyang Ruan 《水文研究》2021,35(4):e14163

Understanding the hydrological processes of colloids within the karst vadose zone is vital to the security of karst groundwater and providing appropriate paleohydrological explanations of colloid-facilitated metals in speleothem. This study addresses the mobilization mechanisms driving colloidal organic matter (COM) transport in the karst vadose zone using a 15-year long monthly monitoring dataset from a cave drip point (HS4) in Heshang Cave, Qingjiang Valley, China. Variations in COM concentrations were reported as the fluorescence difference values of raw and filtered (<0.22 μm) samples at an excitation wavelength of 320 nm and emission wavelength of ~400 nm. A fluorescence humification index (HIX) lower than 0.8 and an autochthonous index (BIX) higher than 1.2 indicated that the origin of COM was mainly from the karst vadose zone, rather than the soil zone. The COM concentration varied from 0.001 to 0.038 Raman Unit (RU), with evident seasonal fluctuations. Rising limbs for COM values occurred prior to rising limbs within a dripwater hydrograph; moreover, the COM peak values corresponding to the beginning of the increasing hydrograph generally suggested that the mobilization of COM reflected the movement of the air–water interface (AWI) in the karst vadose zone rather than rainfall intensity or flow velocity. COM peak values were positively correlated with the antecedent drying duration and negatively correlated with HIX values. These phenomena may be explained by the increased amount of organic matter that was aggregated and absorbed on the surface of carbonate in the karst vadose zone during a longer drying duration. Moreover, the longer drying duration was also beneficial to autochthonous biological activity, which subsequently decreased the HIX value of the organic matter in the karst vadose zone. The movement of AWI and the drying duration are both controlled by the outside weather conditions. This study is therefore conducive to evaluating the security of karst groundwater in response to climate change, and challenges prevailing paleoclimate interpretations of colloid-facilitated metal abundance timeseries reported from speleothems.  相似文献   

甘肃北山老金厂金矿床载金矿物特征、原位硫同位素组成及其对成矿的指示意义     

黄式庭  于晓飞  吕志成  刘家军  李永胜  杜泽忠  吕鑫  孙海瑞  杜轶伦 《吉林大学学报(地球科学版)》2020,50(5):1387-1403

老金厂金矿床是北山成矿南带最具代表性的中低温岩浆热液型金矿床之一，其规模为中型。依据脉体穿插、矿物共生组合和矿石结构构造等特征，将矿床矿化作用过程划分为石英-黄铁矿阶段（Ⅰ）、石英-含砷黄铁矿-毒砂阶段（Ⅱ）、石英-黄铁矿-多金属硫化物阶段（Ⅲ）和石英-方解石阶段（Ⅳ）。利用电子探针研究了不同成矿阶段载金矿物的元素组成及其分布规律。Ⅰ阶段：黄铁矿以粗粒自形立方体为主，粒度为0.50~1.50 mm，贫As、Au；毒砂含量极少，呈细粒他形。Ⅱ阶段：含砷黄铁矿周围常有大量毒砂产出，含砷黄铁矿多为立方体、五角十二面体，粒度为0.30~1.00 mm，富As、Au；该阶段矿化最为强烈，毒砂主要形成于此时期，多呈棱柱状、柱状、放射状集合体，显示富S亏As特征。Ⅲ阶段：多以黄铁矿-黄铜矿-闪锌矿共生组合脉的形式产出，黄铁矿多呈长条状，以富S、Cu、Zn、Au和贫Fe、As为特征。Ⅳ阶段：矿化作用极弱，毒砂、黄铁矿含量极少，为细粒他形。原位硫同位素组成显示：Ⅰ阶段黄铁矿δ³⁴S_V-CDT值为-3.8‰~-2.9‰，均值为-3.3‰；Ⅱ阶段黄铁矿和毒砂δ³⁴S_V-CDT值为-4.7‰~2.6‰，均值为-3.3‰；Ⅲ阶段黄铁矿和闪锌矿δ³⁴S_V-CDT值主要分布于-1.9‰~1.0‰之间，均值为0.1‰。此3个阶段硫同位素组成反映了成矿期硫主要来源于幔源岩浆，混入了部分地层硫。综合前人研究成果，认为成矿早期至晚期，成矿流体总体上由富S贫As向富As贫S演化。Ⅰ阶段体系处于中性稳定的环境，硫源充足；Ⅱ阶段为贫S富As的高氧逸度环境，由于大气降水对地层的淋滤渗透，混入富As流体，Au可能与As结合形成Au-As络合物，在成矿有利部位富集沉淀；Ⅲ阶段成矿元素种类丰富，体系为富S贫As的弱还原环境，Au很可能与HS^-、S^-形成络合物进入黄铁矿晶格。  相似文献   

海域金矿找矿方法研究——以山东省莱州市三山岛北部海域金矿为例     

田振环 《地质学报》2019,93(S1):19-28

莱州市三山岛北部海域金矿区是世界上第一个查明的海域岩金矿。它通过追索延伸至海域的三山岛断裂，圈定破金找矿靶区。利用海域高精度磁测和浅地层剖面测量配合海上钻探，找到了海域大型金矿。以三山岛海域金矿普查为依托，研究出来的这套海域金矿找矿方法和海上钻探平台，可为今后开展海域金及其它与断裂有关的矿产资源找矿，提供指导和借鉴。  相似文献   

辽东铀成矿带连山关地区韧性剪切带与铀成矿作用     

吴迪  刘永江  李伟民  常瑞虹 《岩石学报》2020,36(8):2571-2588

连山关地区位于华北克拉通北缘铀成矿省辽东铀成矿带，已知铀矿床（点）均发育在韧性剪切带附近。为了解韧性剪切带运动学、几何学构造变形机制及与铀矿的关系，本文以连山关岩体周缘韧性剪切带为研究对象，通过野外宏观调查和室内微观研究相结合的研究方法，探讨构造变形期次、韧性剪切带形成机理及其对铀成矿的控制作用。研究表明：连山关岩体周缘发育的韧性剪切带与近南北向挤压构造变形有关，其右行韧性剪切带应变类型为压扁应变，属于一般压缩-平面应变范围，Flinn指数K值在0.19~0.69之间，岩石类型属于S/SL型构造岩。研究区内铀矿体均为隐伏盲矿体，主要赋存于沿着连山关岩体和辽河群接触带右行剪切作用形成的背斜褶皱核部，和北东东向断裂关系密切。综合分析认为，连山关岩体南缘北西向韧性剪切带为一级控矿构造，是区内铀矿热液运移的通道，而剪切带边部的晚期北东东向断裂则是铀矿储存空间；铀源可能来自于太古宙古风化壳，并在大型韧性剪切活动（提供热液运移通道）和基性脉岩侵入（提供热源和还原剂）等综合因素作用下运移、富集成矿。  相似文献   

Conversion relationship of rainfall-soil moisture-groundwater in Quaternary thick cohesive soil in Jianghan Plain,Hubei Province,China     

《China Geology》2020,3(3):462-472

The scientific field test site of rainfall-soil moisture-groundwater conversion in Dabie Mountain Area–Jianghan Plain is located in the northern region of the Jianghan Plain, the transition zone between the Dabie Mountain Area and Jianghan Plain. It’s a great field test site to study the material and energy exchange among rainfall, soil moisture, and groundwater of the Earth ’s critical zone in subtropical monsoon climate plain areas. This paper analyzed the connection between rainfall and volume water content (VWC) of soil at different depths of several soil profiles, and the dynamic feature of groundwater was discussed, which reveals the rainfall infiltration recharge of Quaternary Upper Pleistocene strata. The results show that the Quaternary Upper Pleistocene aquifer groundwater accepts a little direct rainfall recharge, while the lateral recharge is the main supplement source. There were 75 effective rainfall events among 120 rainfall events during the monitoring period, with an accumulated amount of 672.9 mm, and the percentages of effective rainfall amount and duration time were 62.50% and 91.56%, respectively. The max evaporation depth at the upper part in Quaternary cohesive soil was no less than 1.4 m. The soil profile was divided into four zones: (1) The sensitive zone of rainfall infiltration within 1.4 m, where the material and energy exchange frequently near the interface between atmosphere and soil; (2) the buffer zone of rainfall infiltration between 1.4 m and 3.5 m; (3) the migration zone of rainfall infiltration between 3.5 m and 5.0 m; and (4) the rainfall infiltration and groundwater level co-influenced zone below 5.0 m. The results revealed the reaction of soil moisture and groundwater to rainfall in the area covered by cohesive soil under humid climate in Earth ’s critical zone, which is of great theoretical and practical significance for groundwater resources evaluation and development, groundwater environmental protection, ecological environmental improvement, drought disaster prevention, and flood disaster prevention in subtropical monsoon climate plain areas.  相似文献   

中-哈-吉-乌天山变形带容矿金矿床:成矿环境和控矿要素与找矿标志     

薛春纪  赵晓波  赵伟策  赵云  张国震  Bakhtiar NURTAEV  Nikolay PAK  莫宣学 《地学前缘》2020,27(2):294-319

天山是全球第二大金矿富集区,世界级和大型-超大型金矿床东西成带横贯中国新疆中部—哈萨克斯坦东南部—吉尔吉斯斯坦—乌兹别克斯坦,构成巨型跨境金成矿带。天山巨型跨境金成矿带和重要金矿床形成的地质环境、成矿的控制要素、找矿勘查的标志都是学术界和工业界高度关注的重大地质和找矿问题。通过广泛、深入地文献调研和境内外天山较全面野外地质矿产调查与研究,本文认为中-哈-吉-乌天山大规模金成矿主体形成于晚石炭世—早二叠世古亚洲洋闭合后的陆块拼贴变形过程,部分形成于中—晚二叠世陆内走滑变形过程。中天山南、北缘古缝合带及其附近的大型脆性/韧-脆性变形带是巨量金成矿的关键控制因素,多期叠加复合成矿是天山变形带容矿金矿床的显著特征。地壳初始富集、构造变形活化、岩浆热液叠加是天山变形带容矿金矿床的主控因素。“碳质细碎屑岩+脆韧性变形带+海西末期岩体”是中-哈-吉-乌天山变形带容矿大型-超大型金矿的找矿标志组合。  相似文献   

东海盆地中、新生代盆架结构与构造演化   总被引：6，自引：0，他引：6  

刘金水  许怀智  蒋一鸣  王军  何新建 《地质学报》2020,94(3):675-691

基于地貌、钻井、岩石测年和地震等资料,分析盆地地层分布、盆架结构、构造单元划分和裂陷迁移规律,结果表明东海盆地由台北坳陷、舟山隆起、浙东坳陷、钓鱼岛隆褶带和冲绳坳陷构成,是以新生代沉积为主、中生代沉积为辅的大型中、新生代叠合含油气盆地;古元古代变质岩系构成了盆地的基底。该盆地不仅是印度-太平洋前后相继的动力体系作用下形成的西太平洋沟-弧-盆构造体系域一部分,而且也是古亚洲洋动力体系作用下形成的古亚洲洋构造域和特提斯洋动力体系作用下形成的特提斯洋构造域一部分,晚侏罗世至早白垩世经历了构造体制转换,盆地格局发生重大变革,早白垩世以前主要受古亚洲-特提斯洋构造体制影响的强烈挤压造山和地壳增厚作用演变为早白垩世以来主要受太平洋构造体制控制的陆缘伸展裂陷和岩石圈减薄作用,经历侏罗纪古亚洲-特提斯构造体制大陆边缘拗陷和白垩纪以来太平洋构造体制弧后裂陷两大演化阶段。白垩纪以来太平洋构造体制的弧后裂陷演化阶段可细分为早白垩世至始新世裂陷期、渐新世至晚中新世拗陷期和中新世末至全新世裂陷期。  相似文献   

南海边缘海多金属结核与大洋多金属结核对比     

殷征欣  王海峰  韩金生  吕修亚  沈泽中  陈静  贺惠忠  谢安远  关瑶  董超 《吉林大学学报(地球科学版)》2019,49(1):261-277

本文通过系统对比分析前人研究成果，研究了南海边缘海多金属结核的成矿特征，结果表明：南海边缘海结核的矿物组成与大洋结核相似，均主要由锰相矿物和铁相矿物组成，其中锰相矿物主要为水羟锰矿和钡镁锰矿，铁相矿物主要以无定型铁氧化/氢氧化物形式存在，另外南海边缘海结核中含有大量硅酸盐矿物，表明在南海结核成矿过程中受到大量的陆源碎屑矿物混杂；相对于大洋主要经济成矿区的多金属结核，南海边缘海多金属结核中主要的经济元素如Mn、Cu、Co、Ni和Zn质量分数较低，而亲陆源性元素如Fe、Ti、P、Nb、Pb、Rb、Sc、Ta、Sr、Th和REY（REE和Y）等质量分数较高；南海边缘海多金属结核的元素地球化学特征和REE配分模式显示其为水成成因，并呈现更低的Mn/Fe值；同时南海边缘海结核也具有较快的平均生长速率及较高的δCe正异常，表明其生长在更为氧化的海水环境。虽然较快的沉积物沉积速率和动荡的海水环境影响了南海边缘海结核的成矿，但大量陆源物质进入海洋也为南海边缘海结核提供了丰富的成矿物质来源，便于南海边缘海结核的快速生长成矿。南海边缘海结核富集有Fe、Ti、Pb、Rb、Th和REY等金属元素，同样可以作为极具潜力的海洋矿产资源。南海边缘海多金属结核具有其独特的地球化学特征，与大洋多金属结核存在着明显差异。  相似文献